Asbestos Exposures of Building Maintenance Personnel

Abstract

We have analyzed the maintenance logs maintained by owners of buildings containing asbestos fireproofing and subject to operations and maintenance (O&M) programs to evaluate the risk to maintenance personnel from exposure to airborne asbestos. The logs were kept to document protective measures and exposures of maintenance personnel as they performed routine maintenance during the 1991–1992 period. Four of the buildings were commercial and one was a hospital. All exposure monitoring was performed by contract industrial hygienists using the National Institute for Occupational Safety and Health 7400 protocol for sampling; filter analyses were by phase contrast microscopy in certified laboratories. O&M programs required modest control measures, including spraying of ceiling tiles with amended water, high efficiency particulate air vacuuming of tile edges before entry and after tile replacement, respirator usage, and careful work; negative pressure containment was not used. A total of approximately 500 personal and area samples were obtained during the period of maintenance work. In one building, personal exposures during electrical/plumbing work ranged from 0.000 to 0.035 fiber/cc (f/cc) > 5 μm in length (average work time of one job was 118 minutes); the 8-hour time-weighted average (TWA) was 1.49 × 10⁻² f/cc > 5 μm. Personal exposures during cable running were 0.001 to 0.288 f/cc > 5 μm length (average work time of one job was 169 minutes); the 8-hour TWA was 1.67 × 10⁻² f/cc > 5 μm in length. Personal exposures during heating, ventilation, and air-conditioning work was 0.000 to 0.077 f/cc > 5 μm in length. In this same building, the maximum time any worker spent working above the ceiling was 3.31 percent of his total working time for the period of the log. The TWA for the entire working period covered by the log corrected for this factor was 2.27 × 10⁻³ f/cc > 5 μm. Exposure results for the other buildings differed little from results cited above. If minimum O&M procedures are followed by knowledgeable, careful workmen, their TWA exposures to asbestos-in-air from asbestos-containing fireproofing while they work above the ceiling are well below the Occupational Safety and Health Administration 8-hour permissible exposure limit for the period of their work.